.box {
  width: 16rem;
  height: 16rem;
  position: absolute;
  top: 12.9375rem;
  left: 50%;
  transform: translateX(-50%);
  -webkit-transform: translateX(-50%);
  -moz-transform: translateX(-50%);
  -ms-transform: translateX(-50%);
  -o-transform: translateX(-50%);
}

.box .outer {
  width: 100%;
  height: 100%;
  position: absolute;
  z-index: 1;
  top: 0;
  left: 0;
  transform: rotate(0deg);
  -webkit-transform: rotate(0deg);
  -moz-transform: rotate(0deg);
  -ms-transform: rotate(0deg);
  -o-transform: rotate(0deg);
}

.box .outer img{
  width: 100%;
}

.box .inner{
  position: relative;
  width: 5rem;
  height: 5rem;
  left: 50%;
  top: 50%;
  -webkit-transform: translate(-50%, -50%);
  -moz-transform: translate(-50%, -50%);
  -ms-transform: translate(-50%, -50%);
  -o-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
  z-index: 2;
  background-image: url(http://cdn.50yoga.cn/pics/public/sweet/images/chinaYoga/lotteryBtn.png);
  background-size: auto 5rem;
  background-repeat: no-repeat;
}
.box .inner.start:active{
  -webkit-transform: translate(-50%, -50%) scale(.95);
  -moz-transform: translate(-50%, -50%) scale(.95);
  -ms-transform: translate(-50%, -50%) scale(.95);
  -o-transform: translate(-50%, -50%) scale(.95);
  transform: translate(-50%, -50%) scale(.95);
}

.box .inner.start{
  background-position: 0 0;
}
.box .inner.no-start{
  background-position: -5rem 0;
}
.box .inner.completed{
  background-position: -10rem 0;
}
